Don’t let fertility fall away at grass (Feed 4 Thought issue 10)
Swapping a straight oil product for one containing a balance of oils including omega 3’s EPA & DHA will help improve dairy cow fertility according to David Bonsall, UFAC UK Regional Sales Manager in Scotland and the North of England. Once cows are out on grass, the focus for many farms will be on getting good yields from minimal feed rates to maximise margins. However, it is also essential to make sure there is no dip in fertility as the long term consequences can soon outweigh the short term gains. Getting cows back in calf quickly, based on strong exhibition of heat and high conception rates with low levels of embryo mortality must remain high on every farmer’s list of priorities this spring and summer.
One way to help ensure good fertility is to make sure cows are receiving the essential fatty acids they require, in particular the principal omega 3’s EPA and DHA. Grazed grass is low in these fatty acids. Research shows that ensuring cows are receiving sufficient amounts of omega 3 fatty acids from marine sources along with achieving the optimal 4:1 ratio of omega 6: omega 3 can have a significant effect on fertility without adding markedly to diet cost. Omega 3’s EPA & DHA play vital roles in dairy cow fertility. The first role is ensuring strong follicles which results in larger, more viable eggs and increased strength of bulling behaviour. Together, these will help reduce calving to conception interval.
The second role is in reducing embryo mortality. Early embryo loss is a major contributor to extended calving to conception intervals, reduced pregnancy rates and increased culling. These specific omega 3’s, stimulate higher levels of progesterone and lower levels of prostaglandin at time of conception, which together help reduce early embryo mortality. For example, feeding Omega 3 Supplement would be beneficial to cows as it is specially formulated to ensure they receive energy and sufficient omega 3’s. This will help ensure the optimum omega 6: omega 3 ration of 4:1 is achieved, helping ensure fertility remains at high levels while cows are on grass. This should maximise the short term benefits, while avoiding longer term knocks to production due to fewer fresh calvers.
Welcome from Robert Jones, MD
The milk price increases have certainly had the desired effect. Production has increased, so much so that week on week it is now close to the same week last year despite being 8% below as recently as October? But don’t assume prices will remain high. If dairies find they have more milk than they can handle and if spot prices come under pressure, it is likely price rises will stall and, in the worst case scenario may fall back again. Equally don’t be seduced into chasing milk quality, just because your processor asks you to. It is imperative to do the sums first to ensure a return on investment. Dairy farmers have made significant efficiency improvements to help bring about more sustainable costs of production. Now, more than ever before, it is important to retain this focus on efficiency. Your goal is to produce milk at a good margin today and to ensure you get cows in calf to deliver good production and margins tomorrow. Efficiency must remain the number one priority and this means making sure everything you buy, especially feed, delivers a positive return. The summer offers a great opportunity to rebuild margins, and cash reserves, through efficient production, to secure high quality forage for next winter and with plenty of cows in calf. The challenge is to grasp that opportunity. Our team is here to help deliver efficient and effective diets and we will be delighted to offer a second opinion on your dairy rations.
Butterfat yield not percent should be target when cows are on spring grass
UFAC- UK National Sales Manager Mike Chown advises caution before following processor pressure to increase butterfat percent. While some processors are pushing farmers to increase milk quality at grazing, he says producers must ensure it is cost effective and should not over- estimate the potential responses claimed by some ingredient suppliers. Numerous factors work against producing high butterfat percent at grazing. Butterfat requires the production of acetate in the rumen to supply lipogenic energy. At grass, where effective fibre levels are low the rumen tends towards a glucogenic fermentation which will drive milk yield rather than butterfat.
Furthermore modern Holstein cows are genetically geared to produce around 3.6% fat. So producing higher fat percent at grass will be a challenge and in many cases the price paid per additional percent might be insufficient to cover additional costs. Most contracts have a price per percent paid up to a base level. Butterfat increases above this attract a lower pence per percent rate which declines as butterfat increases. In one example contract, butterfat content up to the base level of 3.5% is paid at 3.75p/%. From 3.5-4.0% the rate is 1.75p/% while above 4.0% fat the payment is cut again to 0.75p/%. So the starting point before taking any action to increase butterfat must be to understand what you are going to be paid. One strategy which can be more profitable is to work with the cows and optimise what grass can deliver by looking to maintain or improve milk yield to increase total weight of solids, which is, after all what you are effectively paid for. For most herds, the most efficient way to influence milk quality in order to maximise the milk contract is to focus on fat yield produced (kg fat/day) rather than butterfat percent.
To do this requires a minimum 65% of the rumen VFA’s produced to be acetate and 17% butyrate. Dietary factors affecting acetate and butyrate are effective structural fibre in the diet, VFA’s from conserved forages, the forage to concentrate ratio, the type of concentrates fed and rumen pH. For an efficient rumen and increased milk volume we also require a minimum level of 15% propionate in the total rumen VFA’s. Propionate is required as it is the precursor for glucose which is the major energy source for the cow and milk lactose production, so driving milk yield. Factors affecting propionate production are starch, sugar and non-fibre carbohydrates in the ration. High levels of propionate will give good yields with lower milk fat – and this is what grazing delivers. A careful balancing of the total ration to achieve optimum milk yield and butterfat is critical.
What about feeding more dietary fat?
There has been a lot of talk in the press about feeding higher levels of dietary C16:0 fat to boost butterfat percentage, but the numbers don’t stack up. At current prices this is unlikely to leave room for an increase in margins. Currently C16:0 fat is costing around £1150/tonne on farm, or £1.15 per kilo. At a typical feed rate of 300g, you are looking at a 34p increase in feed costs. Despite talk of an increase of 0.4% butterfat, a more realistic expectation would be an increase of no more than 0.3% extra fat. Using the contract example from earlier on, and assuming a farm is above the base level of 3.5% fat but below 4.0%, the potential costs and returns are shown in the table.
|Feed rate of C16:0 (G/day)||300g|
|Cost/cow/day at £1150/tonne (p/cow)||34p|
|Milk fat response (%)||+0.3%|
|Increase price/litre @1.75p/%||+0.47p/l|
|Extra income for a 30 litre cow||14.1p/l|
|Loss per cow per day||19.9p|
It is often argued that C16:0 fat will increase milk yield too and at 39MJ/ kg you are certainly feeding enough for an extra two litres on paper. However, this energy is not directly available to the cow and does not contribute to the VFA’s and other energy sources the cow needs. It mainly influences milk fat content and contributes to excess body weight loss.
More milk can increase fat production cost-effectively Grazed grass will drive milk yields and provided the rumen function is optimal it will be possible to avoid any butterfat depression. This will actually produce more kilos of butterfat than chasing butterfat percent.
Taking our example 30 litre cow, at 3.7% fat, the cow would produce 1110g of fat per day. At 4.0% fat, the typical increase from feeding C16:0, this will increase to 1200g. If by maximising the rumen function yield is increased to 32 litres at 3.8% fat, she will produce 1216g of fat with lower feed costs, meaning the milk will generate more margin. The key will be to promote efficient use of grass to support higher yields is maintaining rumen health by providing effective structural fibre to complement grazing. In addition it is important to ensure the diet contains the correct balance of energy and protein. As grazed spring grass is high in rumen degradable protein, purchased feeds need to supply DUP and Promega is an ideal feed in this situation. The correct protein sources will help support milk yield and protein production. When selecting a fat supplement, UFAC has developed a more cost effective product to optimise yield of solids. Omega Cream is a rumen inert high C16:0 product with a unique combination of fatty acids including omega 3’s, plus Glycerine to maximise feed conversion efficiency, herd health and fertility.
Check list for good rumen health, efficiency and profitability
The rumen is the engine of cost-effective milk production. The better it is working and utilising the diet to supply the nutrients the cow needs, the more profitable milk production will be. And the healthier your cows will be too. Mark Townsend UFAC-UK sales manager in the south says there are several indicators which can give a good idea of how the rumen is performing and help improve rumen health in those critical fresh calved cows. By checking these areas it will be possible to identify where problems may be occurring. If problems are in the first 21 days of lactation, the source of the problem is more likely to be in the transition diet. If problems are occurring later, around 21 – 60 DIM, this would suggest it is the fresh calved diet which needs reviewing.
Start by looking at rumination signs. To achieve an efficient rumen it is essential to keep the pH around the optimum of 5.8-6.4. Cows on a balanced diet need to produce at least 150 litres of saliva per day, but in an acid ration this requirement can double. Look for:
- At least 7/10 cows cudding an hour after feeding
- 60 cuds per minute
- 15 cuds per swallow
If any of these targets are not met, it is highly likely the rumen is performing inefficiently. Dung consistency and levels of undigested feed in the dung are also good tools to decide whether or not the rumen is working efficiently.
Take a close look at your milk records
Using data already reported by NMR and CIS you can evaluate fresh cow energy status. The milk fatty acid profile in particular can be a good indicator of the type of fermentation being achieved in the rumen, whether acetic, butyric or propionic, and can be used to determine animal health, rumen function and potential milk solids.
- Short chain Fatty Acids Levels over 9% show that rumen function is adequate. Levels below this are an indication of insufficient scratch factor in the diet or too little starch and sugar in the transition diet.
- The levels of C18:1 cis 9 and mono unsaturated fats (MUFAs) Ideally C18:1 cis 9 should be below 22% of total milk fat with MUFAs being below 30%. If levels exceed these, it is an indication that the cow is losing too much body condition daily. In these cases, total energy intake needs to be examined.
- Milk lactose Lactose concentration can vary from c.3.5-4.9%. The minimum in early lactation cows should be 4.5% and ideally should be over 4.6%. If lactose is low, then check energy supply and particularly the extent of propionic fermentation in the rumen. Milk lactose can also be reduced if cows are fighting infection, as glucose is diverted to boost the immune system.
- Milk protein A fall in milk protein to below 3.2% can signal cows are short of DUP and essential amino acids. This commonly occurs when cows have lost so much condition in early lactation that they have mobilised muscle as well as fat, and are using protein in the diet to rebuild muscle. In such cases look at by pass protein and energy levels in the diet to try and reduce condition loss and negative energy balance.